Process for the recovery of aromatic compounds



Patented an. e, 1923.

errata STATES rnanc'is x. GOVERS, or NEW YORK, n. Y.

PROCESS FOR THE RECOVERY OF AROMATIC COMPOUNDS.

No Drawing.

To all whom it may concern:

Be it known that I, FRANCIS X. Govnns, residing at 800 Riverside Drive,borough of Manhattan, city, county, and State of New York, a citizen ofthe United States, have invented certain new and useful Improvements inProcesses for the Recovery of Aromatic Compounds, of which the followingis a specification. i

My process relates to the'recovery of aromatic compounds from mixturesor solutions of same with saturated or unsaturated non-aromatichydrocarbons.

Inthe breaking down of high boiling point hydrocarbonsof the paraffin ornaphthene series into aromatic hydrocarbons, there are formed at thesame time a number of parafiins and unsaturated hydrocarbons of the sameor approximately the sameboiL' ing points as the aromatic compoundssought for. These unsaturated compounds and compounds of the paraffin.series are difficult, if not impossible, to separate from the aromatichydrocarbons desired by fractional distillation and while bytreatmentwith acid andsubsequent treatment with caustic-soda and washingthe unsaturated compounds may be eliminated, they are frequently presentto such an extent as to require a very largeamount of acid for theirremoval. The presence of either unsaturated compounds or co-m-' poundsof the paraffin series with aromatic compounds interferes with many usesof such compounds; for example in the manu facture of explosives, itseriously hinders the process .of nitration and certain amounts of bothor either of these compounds make it, if not impossible to nitrate, atleast a dangerous undertaking. I have found that a quick and easy methodof separating both unsaturated compounds and paraflin compounds from thearomatic hydrocarbons wanted is to subject the mixture to fractionaldistillation, and take fractions around the boiling point of thehydrocarbon desired; for instance, in case benzol is wanted, a cut maybe taken from .78? to 82 C. and in case toluol is wanted, a cut from 108to 112 C. The respective cut or cuts so made are then subjected to aheattreatment advantageously under pressure. This heat Application filedAugust 8, 1918. Serial No. 248,908.

treatment is so conducted in reference to the lower compoundhydrocarbons and then the,

aromatic compound desired, leaving behind th: high boilingpoint'polymerized produc s.

The following. is an example of the foregoing process: A fractionobtained from distillation of the product derived fromcrackingCalifornia petroleum, such fraction distilling between 108 and112 C. and containing some unsaturated hydrocarbon compounds and othercompounds of the paraffin series is subjected to heat treatment in atube furnace at a temperature of approximately 525 C. and a pressure ofabout 500 lbs. T'histemperature and pressure is such that the aromaticcompounds are not changed but the unsaturated compounds and thecompounds of the parafl'in series are changed in the treatment to eitherlower boiling pointc-ompounds' or higher boiling point compounds. Theproduct of the heat treatment is then subjected to fractional(listillation and the desired aromatic compounds recovered substantiallyfree from contaminating compounds. It will be obvious from the foregoingthat many variations may be made in the details of operation withoutdeparting from the spirit and scope of my invention.

What I claim is:

1. In the process of purifying an aromatic compound in a mixture ofsubstantially uniform boiling point containing ,it and contaminatingnon-aromatic hydrocarbon compounds having substantially the sameboiling' point, subjecting said mixture to heat treatment underconditions of temperature and pressure such as to change thecontaminating substances to compounds of higher or' lower boiling pointwithout changing the aromatic compounds desired.

2. In the process of purifying aromatic compounds in mixture containingthem and contaminating non-aromatic hydrocarbon compounds havingsubstantially the same boiling points as the respective aromaticcompounds desired, subjecting the mixture to fractional distillation toobtain mixtures of substantially uniform boiling point of the respectivearomatic compounds with contaminating non-aromatic compoundshavingsubstantially similar boiling points and subjecting the respectivemixtures to heat treatment under conditions of temperature and pressuresuch as to change the contaminating substances to compounds of higher orlower boiling point Without changing the aromatic compounds desired.

FRANCIS X. GO-VERS.

